I have not flagged it, so I am speculating. But users flagging stories is the most common reason stories with a lot of points leave the front page.

These types of stories tend to get user flags for two reasons: they are more voyeaurism than news, and the actual discussions often become flame wars. Also note that I am not a mod, I've just been here for a while.

There was some talk about them not being appropriate for HN, because it was all hearsay within a fairly tightly-knit group. However, none of them were flagged, as far as I know. I don't know what flagging means on HN - this post is marked as flagged and I had to search for it to find it(I was planning on posting the same thing).